Preparation of chromium oxychloride, crocl



United States Patent Office 3,134,640 Patented May 26, 19*64 3,134,640 PREPARATION OF CHROMIUM GXYCHLORIDE, CrGCl Frank W. Hengeveld and Kirman Taylor, Painesville,

Qhio, assignors to Diamond Alkali Company, Cleveland, Ohio, a corporation of Delaware No Drawing. Filed June 8, 1961, Ser. No. 115,786

3 Claims. (Cl. 23-85) It was obtained by heating chromium (III) chloride hexahydrate at red heat. At that time, it was not established whether the material was a true chemical compound of constant composition or merely a mixture of chromium oxides and chlorides.

An object of this invention, therefore, is to prepare chromium (III) oxyhalides as chemical entities of definite composition.

A further object is to provide an economical method for preparing chromium (Ill) oxyhalides in a state of substantially high purity.

These and other objects will become apparent to those skilled in the art upon reading the description of the invention which follows.

The present invention is directed to the process of preparing a compound of the formula CrOX, wherein X is a halogen, which comprises reacting a compound of the formula CrX with oxygen. Commercial oxygen is conveniently used; however, air may also be employed as an oxygen source.

The reaction may be carried out by passing air or oxygen through solid anhydrous chromium (III) halide, the latter being heated to a temperature of about 200500 C., preferably 300450 C. Oxygen may be fed to the chromium halide at any convenient rate, typically about 5-15 liters per hour. The time required for substantially complete conversion to chromium oxyhalide is usually from three to five hours, and is best determined by observation. If too much oxygen is used, the characteristic green color of chromium (III) oxide, Cr 0 appears in the product. Reaction rate and extent of product formation are dependent upon the particle size of the chromium (III) halide; a material oi small particle size is more completely converted to oxyhalide in a shorter time than is a material of larger particle size.

Alternatively, the reaction may be carried out by passing a mixture of oxygen and an inert gas, e.g., helium or nitrogen, through a bed of chromium (III) halide. The same conditions of temperature, time and addition rate apply.

When, for example, chromium (III) chloride is reacted with oxygen by the method set forth hereinabove, the product, chromium (III) oxychloride, is obtained as a gray powder with a bulk density of about 0.02O.5 g. per cc., depending on the bulk density of the chromium (III) chloride used. The compound is in the form of hair-like crystals. X-ray diffraction data show that the crystalline structure of chromium (III) oxychloride is distinctly different from those of Cr O and CrCl The high surface area of chromium (III) oxychloride suggests utility as a catalyst, catalyst support, thermal insulator, and filler for plastics, rubber and the like. In the presence of aluminum alkyls, it has been shown to be an effective catalyst for the polymerization of olefins.

In order that those skilled in the art may more commethods by which the same may be carried into effect, the following specific examples may be oifered:

EXAMPLE I Preparation of Chromium (III) Oxychloride A Z-liter, 3-necked, round-bottomed flask is fitted with a mechanical stirrer and gas inlet and exit tubes. The flask is half filled with anhydrous chromic chloride and is heated with a heating mantle until the surface of the flask has reached a temperature of 450 C. The chromic chloride is slowly agitated as oxygen is fed to the reactor for 3 /2 hours at a rate of 6 to 10 liters per hour. After 30 minutes of reaction, the flask is filled with a reddish brown gas, probably chromyl chloride. At the end of the reaction, essentially all of the chromic chloride has been converted to gray crystals of chromium (III) oxychloride.

Elemental analysis of the product indicates an atomic ratio of 1:111 for chromium, oxygen and chlorine. The line spacings in the X-ray powder patterns for the product of this example and the known oxides and chlorides of chromium are markedly different, thus proving the existence of CrOCl as a distinct chemical species.

EXAMPLE II Part A.H0m0polymerization Polymerizations of ethylene, propylene, and ethylenepropylene mixtures are carried out in 7-oz. bottles. The bottle is charged with 100 ml. of heptane and 1 millimole of chromium (III) oxychloride and then sealed. Two millirnoles of triisobutyl aluminum in dilute solution is then injected into the bottle by means of a hypodermic syringe. The monomer (ethylene, propylene, or a 1:4 molar ratio of ethylene to propylene) is then charged to the bottle to a total monomer pressure of p.s.i. The polymerization is allowed to continue for 24 hours at 25" C., followed by 72 hours at 75 C. The results of this experiment are shown in the following table.

Code: 0n0 polymerization; 1-traces of polymer 2yield about 0.1 g.; 3yield about 1 g.; 4=yield about 3 g.; p polymerization on solid particles; .=spo1ymer-izatlon in solu- Part B.C0p0lymerizati0n Ethylene and propylene (1 :4 molar ratio) are copolymerized in the presence of a chromium oxychloride-triisobutyl-aluminum catalyst. The polymerization is carried out according to the procedure described in Part A. In a 30-ounce bottle are placed 600 cc. of heptane, 2 milli moles of chromium oxychloride, and the required amount of triisobutylaluminum to give the molar ratio designated in the table below. The bottle is then charged with a 1:4 mixture of ethylene and propylene to a monomer pressure of 50 p.s.i. and polymerization is allowed to take place for 12 hours at C. The results are given below.

Molar ratio, Al(i-Bu) :CrOCl: Yield 1.5:1 3 2:1 3 3:1 4 5:1 4 10:1 4

It is to be understood that although the invention has been described with specific reference to particular embodirnents thereof, it is not to be so limited, since changes 3 and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claims.

What is claimed is:

1. The process of preparing chromium oxychloride having the formula CrQCl, which comprises reacting chromic chloride with oxygen for about three to five hours, with agitation, at a temperature of about 20 to 500 C. and recovering the chromium oxychloride.

2. The process of preparing chromium oxychloride having the formula CrOCl, which comprises reacting chromic chloride with oxygen at a temperature of about 300 to 450 C. for a period of about three to five hours, with agitation, and recovering the chromium oxychloride.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Mellor: Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. 11, pages 391-2 (1931). Long- 3. The process of preparing chromium oxychloride 15 mans, Green&Company, New York.

having the formula CrOCl, which comprises heating anhydrous chrornic chloride to a temperature of about 200 to 500 C., with agitation, introducing oxygen for a period of about three to five hours at a rate of about 5 Jacobsons Encyclopedia of Chemical Reaction, vol. 2, 194-8 Edition, page 748 (Eq. II 2960). Reinhold Pub. Corp, New York.

Chemical Reviews, vol. 58, No. 1, pages 4-8 (February to 15 liters per hour and recovering the chromium oxy- 20 1958),

chloride. 

1. THE PROCESS OF PREPARING CHROMIUM OXYCHLORIDE HAVING THE FORMULA CROCL, WHICH COMPRISES REACTING CHROMIC CHLORIDE WITH OXYGEN FOR ABOUT THREE TO FIVE HOURS, WITH AGITATION, AT A TEMPERATURE OF ABOUT 200* TO 500*C. AND RECOVERING THE CHROMIUM OXYCHLORIDE 